Many enterprises have more employees than desks in certain locations. The explanation may be due to a large sales force, many of whom visit the physical office only rarely. It is increasingly important for companies to save cost by not tying up square footage when the employees are elsewhere, especially for companies with sales personnel in high-rent districts. To make desk-sharing practical, a desirable solution is for employees to keep their personal phone extensions even if they use one desk one day and another the next-possibly in different cities. To ensure productivity, employees would also need access to their own telephony feature sets, such as speed-dial numbers and services like Follow-Me, Personal Assistant, and others.
IP telephony is a fast growing application providing low cost communication with others. Because of the integration of IP telephony devices and data networks (e.g., Internet), many innovative features may be possible for users of Voice over IP (VoIP) that have not been available to users of traditional telecommunication networks (e.g., Public Switched Telephone Network).
One such notable feature is Cisco's Extension Mobility, a built-in feature of Cisco Unified CallManager (CUCM). CUCM tracks all active VoIP network components, which include phones, gateways, conference bridges, transcoding resources and voicemail boxes among others. Extension Mobility allows a user to log onto any Extension Mobility-enabled IP phone (e.g., Cisco IP phone 7960) with a user ID and PIN and to transfer his user profile to that phone. It allows the user to configure the Extension Mobility-enable IP phone as his own, on a temporary basis, with line numbers, speed dials, services, permissions, and other user-specific properties. However, only those IP phones served in a single CUCM cluster may participate in Extension Mobility (a cluster may serve a single building or multiple offices across several cities). In other words, the Extension Mobility feature does not allow users to traverse different clusters within a network.
Therefore, there is a need for an IP phone service which can provide seamless mobility across multiple clusters within the enterprise data network domain.